001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.server.namenode;
019
020import java.io.File;
021import java.io.IOException;
022import java.net.URI;
023import java.util.ArrayList;
024import java.util.Collection;
025import java.util.HashMap;
026import java.util.Map;
027
028import org.apache.commons.logging.Log;
029import org.apache.commons.logging.LogFactory;
030import org.apache.hadoop.conf.Configuration;
031import org.apache.hadoop.fs.DF;
032import org.apache.hadoop.hdfs.DFSConfigKeys;
033import org.apache.hadoop.hdfs.server.common.Util;
034
035import com.google.common.annotations.VisibleForTesting;
036
037/**
038 * 
039 * NameNodeResourceChecker provides a method -
040 * <code>hasAvailableDiskSpace</code> - which will return true if and only if
041 * the NameNode has disk space available on all volumes which are configured to
042 * be checked. Volumes containing file system name/edits dirs are added by
043 * default, and arbitrary extra volumes may be configured as well.
044 */
045public class NameNodeResourceChecker {
046  private static final Log LOG = LogFactory.getLog(NameNodeResourceChecker.class.getName());
047
048  // Space (in bytes) reserved per volume.
049  private long duReserved;
050
051  private final Configuration conf;
052  private Map<String, DF> volumes;
053
054  /**
055   * Create a NameNodeResourceChecker, which will check the name dirs and edits
056   * dirs set in <code>conf</code>.
057   * 
058   * @param conf
059   * @throws IOException
060   */
061  public NameNodeResourceChecker(Configuration conf) throws IOException {
062    this.conf = conf;
063    volumes = new HashMap<String, DF>();
064
065    duReserved = conf.getLong(DFSConfigKeys.DFS_NAMENODE_DU_RESERVED_KEY,
066        DFSConfigKeys.DFS_NAMENODE_DU_RESERVED_DEFAULT);
067
068    Collection<URI> extraCheckedVolumes = Util.stringCollectionAsURIs(conf
069        .getTrimmedStringCollection(DFSConfigKeys.DFS_NAMENODE_CHECKED_VOLUMES_KEY));
070
071    addDirsToCheck(FSNamesystem.getNamespaceDirs(conf));
072    addDirsToCheck(FSNamesystem.getNamespaceEditsDirs(conf));
073    addDirsToCheck(extraCheckedVolumes);
074  }
075
076  /**
077   * Add the passed-in directories to the list of volumes to check.
078   * 
079   * @param directoriesToCheck
080   *          The directories whose volumes will be checked for available space.
081   * @throws IOException
082   */
083  private void addDirsToCheck(Collection<URI> directoriesToCheck)
084      throws IOException {
085    for (URI directoryUri : directoriesToCheck) {
086      File dir = new File(directoryUri.getPath());
087      if (!dir.exists()) {
088        throw new IOException("Missing directory "+dir.getAbsolutePath());
089      }
090      DF df = new DF(dir, conf);
091      volumes.put(df.getFilesystem(), df);
092    }
093  }
094
095  /**
096   * Return true if disk space is available on at least one of the configured
097   * volumes.
098   * 
099   * @return True if the configured amount of disk space is available on at
100   *         least one volume, false otherwise.
101   * @throws IOException
102   */
103  boolean hasAvailableDiskSpace()
104      throws IOException {
105    return getVolumesLowOnSpace().size() < volumes.size();
106  }
107
108  /**
109   * Return the set of directories which are low on space.
110   * @return the set of directories whose free space is below the threshold.
111   * @throws IOException 
112   */
113  Collection<String> getVolumesLowOnSpace() throws IOException {
114    if (LOG.isDebugEnabled()) {
115      LOG.debug("Going to check the following volumes disk space: " + volumes);
116    }
117    Collection<String> lowVolumes = new ArrayList<String>();
118    for (DF volume : volumes.values()) {
119      long availableSpace = volume.getAvailable();
120      String fileSystem = volume.getFilesystem();
121      if (LOG.isDebugEnabled()) {
122        LOG.debug("Space available on volume '" + fileSystem + "' is " + availableSpace);
123      }
124      if (availableSpace < duReserved) {
125        LOG.warn("Space available on volume '" + fileSystem + "' is "
126            + availableSpace +
127            ", which is below the configured reserved amount " + duReserved);
128        lowVolumes.add(volume.getFilesystem());
129      }
130    }
131    return lowVolumes;
132  }
133  
134  @VisibleForTesting
135  void setVolumes(Map<String, DF> volumes) {
136    this.volumes = volumes;
137  }
138}